Unity Shader - UI/Default shader 优化示例

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环境

Unity : 2020.3.37f1
Pipeline : BRP

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优化

做性能优化都是慢慢都扣出来的

当然，优先处理 top 热点的

但是一些就算不是 top，但是像素面积有多，overdraw 也多不可小觑

当然，如果你能找到性能热点，那还是优先分析一下哪些 shader 占的 cycles 最高，和 A, L/S, T, 最高

还有 register 的数量尽可能的少

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示例

比如： UI/Default 的 shader
下面优化的是一些小部分的内容，不是 top 热点，优化原理是一样的

优化选项：

• 浮点精度
• 避免类型转换
• 避免 laster z （一般是 alpha test 导致，或是 sv_depth 的深度操作）
• 删除无用的效果代码
• 删除不明显的效果代码
• 优化写法（这个一般需要了解一些 编译器 无法识别的 编译优化时，需要特殊处理）

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Texture Format : Alpha 8 和 shaderlab : _TextureSampleAdd

如果确保项目中没有使用到 texture 的格式为 Alpha 8 的 UI 纹理，那么可以将 _TextureSampleAdd 删除

但是 _TextureSampleAdd 文档根本没有说明
cginc 或是 shader 文件也没有表述，这就很 Unity

因此之前压根不敢删除

谷歌 搜索了一下，找到：
What does _TextureSampleAdd do?

然后确定我们项目中不使用到 Alpha 8 格式的 UI 纹理，那么就可以直接使用了

看到了回答：

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shaderlab : _UIMaskSoftnessX 和 _UIMaskSoftnessY

如果项目中的 RectMask2D 也没有使用到 软裁剪，也可以将 UI/Default 中的 _UIMaskSoftnessX 和 _UIMaskSoftnessY 删除

Softness 开启

Softness 关闭

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shaderlab _Color

这块比较容易忽略，虽然只是 vs 的计算，而且 UI 的顶点数量不多，一般不是什么问题
但还是那句话，性能如果要做到极致，除了优化 top 热点，其余小的也是肉，能优化就优化

所以，如果项目中 UI/Default 使用了 _Color，但是项目中没去使用，那就可以删除
一般都是使用unity 自带的按钮状态来控制（这些是通过 vertex buffer 来控制的，因为这样可以 vertex buffer 合批）

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shader

// Unity built-in shader source. Copyright (c) 2016 Unity Technologies. MIT license (see license.txt)

Shader "UI/Default"
{
    Properties
    {
        [PerRendererData] _MainTex ("Sprite Texture", 2D) = "white" {}
        _Color ("Tint", Color) = (1,1,1,1)

        _StencilComp ("Stencil Comparison", Float) = 8
        _Stencil ("Stencil ID", Float) = 0
        _StencilOp ("Stencil Operation", Float) = 0
        _StencilWriteMask ("Stencil Write Mask", Float) = 255
        _StencilReadMask ("Stencil Read Mask", Float) = 255

        _ColorMask ("Color Mask", Float) = 15

        [Toggle(UNITY_UI_ALPHACLIP)] _UseUIAlphaClip ("Use Alpha Clip", Float) = 0
    }

    SubShader
    {
        Tags
        {
            "Queue"="Transparent"
            "IgnoreProjector"="True"
            "RenderType"="Transparent"
            "PreviewType"="Plane"
            "CanUseSpriteAtlas"="True"
        }

        Stencil
        {
            Ref [_Stencil]
            Comp [_StencilComp]
            Pass [_StencilOp]
            ReadMask [_StencilReadMask]
            WriteMask [_StencilWriteMask]
        }

        Cull Off
        Lighting Off
        ZWrite Off
        ZTest [unity_GUIZTestMode]
        Blend One OneMinusSrcAlpha
        ColorMask [_ColorMask]

        Pass
        {
            Name "Default"
        CGPROGRAM
            #pragma vertex vert
            #pragma fragment frag
            #pragma target 2.0

            #include "UnityCG.cginc"
            #include "UnityUI.cginc"

            #pragma multi_compile_local _ UNITY_UI_CLIP_RECT
            #pragma multi_compile_local _ UNITY_UI_ALPHACLIP

            struct appdata_t
            {
                float4 vertex   : POSITION;
                float4 color    : COLOR;
                float2 texcoord : TEXCOORD0;
                UNITY_VERTEX_INPUT_INSTANCE_ID
            };

            struct v2f
            {
                float4 vertex   : SV_POSITION;
                fixed4 color    : COLOR;
                float2 texcoord  : TEXCOORD0;
                float4 worldPosition : TEXCOORD1;
                float4  mask : TEXCOORD2;
                UNITY_VERTEX_OUTPUT_STEREO
            };

            sampler2D _MainTex;
            fixed4 _Color;
            fixed4 _TextureSampleAdd;
            float4 _ClipRect;
            float4 _MainTex_ST;
            float _UIMaskSoftnessX;
            float _UIMaskSoftnessY;

            v2f vert(appdata_t v)
            {
                v2f OUT;
                UNITY_SETUP_INSTANCE_ID(v);
                UNITY_INITIALIZE_VERTEX_OUTPUT_STEREO(OUT);
                float4 vPosition = UnityObjectToClipPos(v.vertex);
                OUT.worldPosition = v.vertex;
                OUT.vertex = vPosition;

                float2 pixelSize = vPosition.w;
                pixelSize /= float2(1, 1) * abs(mul((float2x2)UNITY_MATRIX_P, _ScreenParams.xy));

                float4 clampedRect = clamp(_ClipRect, -2e10, 2e10);
                float2 maskUV = (v.vertex.xy - clampedRect.xy) / (clampedRect.zw - clampedRect.xy);
                OUT.texcoord = TRANSFORM_TEX(v.texcoord.xy, _MainTex);
                OUT.mask = float4(v.vertex.xy * 2 - clampedRect.xy - clampedRect.zw, 0.25 / (0.25 * half2(_UIMaskSoftnessX, _UIMaskSoftnessY) + abs(pixelSize.xy)));

                OUT.color = v.color * _Color;
                return OUT;
            }

            fixed4 frag(v2f IN) : SV_Target
            {
                half4 color = IN.color * (tex2D(_MainTex, IN.texcoord) + _TextureSampleAdd);

                #ifdef UNITY_UI_CLIP_RECT
                half2 m = saturate((_ClipRect.zw - _ClipRect.xy - abs(IN.mask.xy)) * IN.mask.zw);
                color.a *= m.x * m.y;
                #endif

                #ifdef UNITY_UI_ALPHACLIP
                clip (color.a - 0.001);
                #endif

                color.rgb *= color.a;

                return color;
            }
        ENDCG
        }
    }
}

优化后

// Unity built-in shader source. Copyright (c) 2016 Unity Technologies. MIT license (see license.txt)

Shader "UI/Default_EXT"
{
    Properties
    {
        [PerRendererData] _MainTex ("Sprite Texture", 2D) = "white" {}

        _StencilComp ("Stencil Comparison", Float) = 8
        _Stencil ("Stencil ID", Float) = 0
        _StencilOp ("Stencil Operation", Float) = 0
        _StencilWriteMask ("Stencil Write Mask", Float) = 255
        _StencilReadMask ("Stencil Read Mask", Float) = 255

        _ColorMask ("Color Mask", Float) = 15

        [Toggle(UNITY_UI_ALPHACLIP)] _UseUIAlphaClip ("Use Alpha Clip", Float) = 0
    }

    SubShader
    {
        Tags
        {
            "Queue"="Transparent"
            "IgnoreProjector"="True"
            "RenderType"="Transparent"
            "PreviewType"="Plane"
            "CanUseSpriteAtlas"="True"
        }

        Stencil
        {
            Ref [_Stencil]
            Comp [_StencilComp]
            Pass [_StencilOp]
            ReadMask [_StencilReadMask]
            WriteMask [_StencilWriteMask]
        }

        Cull Off
        Lighting Off
        ZWrite Off
        ZTest [unity_GUIZTestMode]
        Blend One OneMinusSrcAlpha
        ColorMask [_ColorMask]

        Pass
        {
            Name "Default"
        CGPROGRAM
            #pragma vertex vert
            #pragma fragment frag
            #pragma target 2.0

            #include "UnityCG.cginc"
            #include "UnityUI.cginc"

            #pragma multi_compile_local _ UNITY_UI_CLIP_RECT
            #pragma multi_compile_local _ UNITY_UI_ALPHACLIP

            struct appdata_t
            {
                float4 vertex   : POSITION;
                fixed4 color    : COLOR;
                half2 texcoord : TEXCOORD0;
                UNITY_VERTEX_INPUT_INSTANCE_ID
            };

            struct v2f
            {
                float4 vertex   : SV_POSITION;
                fixed4 color    : COLOR;
                half2 texcoord  : TEXCOORD0;
                //float4 worldPosition : TEXCOORD1;
                half2  mask : TEXCOORD2;
                UNITY_VERTEX_OUTPUT_STEREO
            };

            sampler2D _MainTex;
            float4 _ClipRect;
            half4 _MainTex_ST;
            half _UIMaskSoftnessX;
            half _UIMaskSoftnessY;

            v2f vert(appdata_t v)
            {
                v2f OUT;
                UNITY_SETUP_INSTANCE_ID(v);
                UNITY_INITIALIZE_VERTEX_OUTPUT_STEREO(OUT);
                float4 vPosition = UnityObjectToClipPos(v.vertex);
                //OUT.worldPosition = v.vertex;
                OUT.vertex = vPosition;

                half2 pixelSize = vPosition.w;
                pixelSize /= half2(1, 1) * abs(mul((half2x2)UNITY_MATRIX_P, _ScreenParams.xy));

                float4 clampedRect = clamp(_ClipRect, -2e10, 2e10);
                //float2 maskUV = (v.vertex.xy - clampedRect.xy) / (clampedRect.zw - clampedRect.xy);
                OUT.texcoord = TRANSFORM_TEX(v.texcoord.xy, _MainTex);
                OUT.mask = half2(v.vertex.xy * 2 - clampedRect.xy - clampedRect.zw);

                OUT.color = v.color;
                return OUT;
            }

            fixed4 frag(v2f IN) : SV_Target
            {
                half4 color = IN.color * tex2D(_MainTex, IN.texcoord);

                //color.rgb *= half3(1.0, 0.1, 0.1);

                #ifdef UNITY_UI_CLIP_RECT
                half2 m = saturate(_ClipRect.zw - _ClipRect.xy - abs(IN.mask.xy));
                color.a *= m.x * m.y;
                #endif

                #ifdef UNITY_UI_ALPHACLIP
                clip (color.a - 0.001);
                #endif

                color.rgb *= color.a;

                return color;
            }
        ENDCG
        }
    }
}

---

ARM Mobile Studio - Graphics Analyzer

vivo 手机 mali gpu 的来测试
AGA 分析一波

优化前

vs:

#version 320 es

#define HLSLCC_ENABLE_UNIFORM_BUFFERS 1
#if HLSLCC_ENABLE_UNIFORM_BUFFERS
#define UNITY_UNIFORM
#else
#define UNITY_UNIFORM uniform
#endif
#define UNITY_SUPPORTS_UNIFORM_LOCATION 1
#if UNITY_SUPPORTS_UNIFORM_LOCATION
#define UNITY_LOCATION(x) layout(location = x)
#define UNITY_BINDING(x) layout(binding = x, std140)
#else
#define UNITY_LOCATION(x)
#define UNITY_BINDING(x) layout(std140)
#endif
uniform 	vec4 _ScreenParams;
uniform 	vec4 hlslcc_mtx4x4unity_ObjectToWorld[4];
uniform 	vec4 hlslcc_mtx4x4glstate_matrix_projection[4];
uniform 	vec4 hlslcc_mtx4x4unity_MatrixVP[4];
uniform 	mediump vec4 _Color;
uniform 	vec4 _ClipRect;
uniform 	vec4 _MainTex_ST;
uniform 	float _UIMaskSoftnessX;
uniform 	float _UIMaskSoftnessY;
in highp vec4 in_POSITION0;
in highp vec4 in_COLOR0;
in highp vec2 in_TEXCOORD0;
out mediump vec4 vs_COLOR0;
out highp vec2 vs_TEXCOORD0;
out highp vec4 vs_TEXCOORD1;
out highp vec4 vs_TEXCOORD2;
vec4 u_xlat0;
vec4 u_xlat1;
void main()
{
    u_xlat0 = in_POSITION0.yyyy * hlslcc_mtx4x4unity_ObjectToWorld[1];
    u_xlat0 = hlslcc_mtx4x4unity_ObjectToWorld[0] * in_POSITION0.xxxx + u_xlat0;
    u_xlat0 = hlslcc_mtx4x4unity_ObjectToWorld[2] * in_POSITION0.zzzz + u_xlat0;
    u_xlat0 = u_xlat0 + hlslcc_mtx4x4unity_ObjectToWorld[3];
    u_xlat1 = u_xlat0.yyyy * hlslcc_mtx4x4unity_MatrixVP[1];
    u_xlat1 = hlslcc_mtx4x4unity_MatrixVP[0] * u_xlat0.xxxx + u_xlat1;
    u_xlat1 = hlslcc_mtx4x4unity_MatrixVP[2] * u_xlat0.zzzz + u_xlat1;
    u_xlat0 = hlslcc_mtx4x4unity_MatrixVP[3] * u_xlat0.wwww + u_xlat1;
    gl_Position = u_xlat0;
    u_xlat1 = in_COLOR0 * _Color;
    vs_COLOR0 = u_xlat1;
    vs_TEXCOORD0.xy = in_TEXCOORD0.xy * _MainTex_ST.xy + _MainTex_ST.zw;
    vs_TEXCOORD1 = in_POSITION0;
    u_xlat0.xy = _ScreenParams.yy * hlslcc_mtx4x4glstate_matrix_projection[1].xy;
    u_xlat0.xy = hlslcc_mtx4x4glstate_matrix_projection[0].xy * _ScreenParams.xx + u_xlat0.xy;
    u_xlat0.xy = u_xlat0.ww / abs(u_xlat0.xy);
    u_xlat0.xy = vec2(_UIMaskSoftnessX, _UIMaskSoftnessY) * vec2(0.25, 0.25) + abs(u_xlat0.xy);
    vs_TEXCOORD2.zw = vec2(0.25, 0.25) / u_xlat0.xy;
    u_xlat0 = max(_ClipRect, vec4(-2e+10, -2e+10, -2e+10, -2e+10));
    u_xlat0 = min(u_xlat0, vec4(2e+10, 2e+10, 2e+10, 2e+10));
    u_xlat0.xy = in_POSITION0.xy * vec2(2.0, 2.0) + (-u_xlat0.xy);
    vs_TEXCOORD2.xy = (-u_xlat0.zw) + u_xlat0.xy;
    return;
}

FS:

#version 320 es

precision highp float;
precision highp int;
#define HLSLCC_ENABLE_UNIFORM_BUFFERS 1
#if HLSLCC_ENABLE_UNIFORM_BUFFERS
#define UNITY_UNIFORM
#else
#define UNITY_UNIFORM uniform
#endif
#define UNITY_SUPPORTS_UNIFORM_LOCATION 1
#if UNITY_SUPPORTS_UNIFORM_LOCATION
#define UNITY_LOCATION(x) layout(location = x)
#define UNITY_BINDING(x) layout(binding = x, std140)
#else
#define UNITY_LOCATION(x)
#define UNITY_BINDING(x) layout(std140)
#endif
uniform 	mediump vec4 _TextureSampleAdd;
uniform 	vec4 _ClipRect;
UNITY_LOCATION(0) uniform mediump sampler2D _MainTex;
in mediump vec4 vs_COLOR0;
in highp vec2 vs_TEXCOORD0;
in highp vec4 vs_TEXCOORD2;
layout(location = 0) out mediump vec4 SV_Target0;
vec4 u_xlat0;
mediump vec4 u_xlat16_0;
mediump float u_xlat16_1;
void main()
{
    u_xlat0.xy = (-_ClipRect.xy) + _ClipRect.zw;
    u_xlat0.xy = u_xlat0.xy + -abs(vs_TEXCOORD2.xy);
    u_xlat0.xy = u_xlat0.xy * vs_TEXCOORD2.zw;
#ifdef UNITY_ADRENO_ES3
    u_xlat0.xy = min(max(u_xlat0.xy, 0.0), 1.0);
#else
    u_xlat0.xy = clamp(u_xlat0.xy, 0.0, 1.0);
#endif
    u_xlat16_1 = u_xlat0.y * u_xlat0.x;
    u_xlat16_0 = texture(_MainTex, vs_TEXCOORD0.xy);
    u_xlat0 = u_xlat16_0 + _TextureSampleAdd;
    u_xlat0 = u_xlat0 * vs_COLOR0;
    u_xlat16_1 = u_xlat16_1 * u_xlat0.w;
    SV_Target0.xyz = u_xlat0.xyz * vec3(u_xlat16_1);
    SV_Target0.w = u_xlat16_1;
    return;
}

---

优化后

VS：

Working Reigster 反而增加1就有点迷

#version 320 es

#define HLSLCC_ENABLE_UNIFORM_BUFFERS 1
#if HLSLCC_ENABLE_UNIFORM_BUFFERS
#define UNITY_UNIFORM
#else
#define UNITY_UNIFORM uniform
#endif
#define UNITY_SUPPORTS_UNIFORM_LOCATION 1
#if UNITY_SUPPORTS_UNIFORM_LOCATION
#define UNITY_LOCATION(x) layout(location = x)
#define UNITY_BINDING(x) layout(binding = x, std140)
#else
#define UNITY_LOCATION(x)
#define UNITY_BINDING(x) layout(std140)
#endif
uniform 	vec4 hlslcc_mtx4x4unity_ObjectToWorld[4];
uniform 	vec4 hlslcc_mtx4x4unity_MatrixVP[4];
uniform 	vec4 _ClipRect;
uniform 	mediump vec4 _MainTex_ST;
in highp vec4 in_POSITION0;
in mediump vec4 in_COLOR0;
in mediump vec2 in_TEXCOORD0;
out mediump vec4 vs_COLOR0;
out mediump vec2 vs_TEXCOORD0;
out mediump vec2 vs_TEXCOORD2;
vec4 u_xlat0;
vec4 u_xlat1;
void main()
{
    u_xlat0 = in_POSITION0.yyyy * hlslcc_mtx4x4unity_ObjectToWorld[1];
    u_xlat0 = hlslcc_mtx4x4unity_ObjectToWorld[0] * in_POSITION0.xxxx + u_xlat0;
    u_xlat0 = hlslcc_mtx4x4unity_ObjectToWorld[2] * in_POSITION0.zzzz + u_xlat0;
    u_xlat0 = u_xlat0 + hlslcc_mtx4x4unity_ObjectToWorld[3];
    u_xlat1 = u_xlat0.yyyy * hlslcc_mtx4x4unity_MatrixVP[1];
    u_xlat1 = hlslcc_mtx4x4unity_MatrixVP[0] * u_xlat0.xxxx + u_xlat1;
    u_xlat1 = hlslcc_mtx4x4unity_MatrixVP[2] * u_xlat0.zzzz + u_xlat1;
    gl_Position = hlslcc_mtx4x4unity_MatrixVP[3] * u_xlat0.wwww + u_xlat1;
    vs_COLOR0 = in_COLOR0;
    u_xlat0 = max(_ClipRect, vec4(-2e+10, -2e+10, -2e+10, -2e+10));
    u_xlat0 = min(u_xlat0, vec4(2e+10, 2e+10, 2e+10, 2e+10));
    u_xlat0.xy = in_POSITION0.xy * vec2(2.0, 2.0) + (-u_xlat0.xy);
    u_xlat0.xy = (-u_xlat0.zw) + u_xlat0.xy;
    vs_TEXCOORD2.xy = u_xlat0.xy;
    vs_TEXCOORD0.xy = in_TEXCOORD0.xy * _MainTex_ST.xy + _MainTex_ST.zw;
    return;
}

FS：

#version 320 es

precision highp float;
precision highp int;
#define HLSLCC_ENABLE_UNIFORM_BUFFERS 1
#if HLSLCC_ENABLE_UNIFORM_BUFFERS
#define UNITY_UNIFORM
#else
#define UNITY_UNIFORM uniform
#endif
#define UNITY_SUPPORTS_UNIFORM_LOCATION 1
#if UNITY_SUPPORTS_UNIFORM_LOCATION
#define UNITY_LOCATION(x) layout(location = x)
#define UNITY_BINDING(x) layout(binding = x, std140)
#else
#define UNITY_LOCATION(x)
#define UNITY_BINDING(x) layout(std140)
#endif
uniform 	vec4 _ClipRect;
UNITY_LOCATION(0) uniform mediump sampler2D _MainTex;
in mediump vec4 vs_COLOR0;
in mediump vec2 vs_TEXCOORD0;
in mediump vec2 vs_TEXCOORD2;
layout(location = 0) out mediump vec4 SV_Target0;
vec4 u_xlat0;
mediump vec4 u_xlat16_0;
mediump float u_xlat16_1;
void main()
{
    u_xlat0.xy = (-_ClipRect.xy) + _ClipRect.zw;
    u_xlat0.xy = u_xlat0.xy + -abs(vs_TEXCOORD2.xy);
#ifdef UNITY_ADRENO_ES3
    u_xlat0.xy = min(max(u_xlat0.xy, 0.0), 1.0);
#else
    u_xlat0.xy = clamp(u_xlat0.xy, 0.0, 1.0);
#endif
    u_xlat16_1 = u_xlat0.y * u_xlat0.x;
    u_xlat16_0 = texture(_MainTex, vs_TEXCOORD0.xy);
    u_xlat0 = u_xlat16_0 * vs_COLOR0;
    u_xlat16_1 = u_xlat16_1 * u_xlat0.w;
    SV_Target0.xyz = u_xlat0.xyz * vec3(u_xlat16_1);
    SV_Target0.w = u_xlat16_1;
    return;
}